Andrea Appiani was born on 23rd May 1754 in Milan. He came from a lower middle-class background. From 1769, he studied under Carlo Maria Giudici in Milan, and then Martin Knoler at the Ambrosiana, at Ospedale Maggiore. From 1776, he trained at the Accademia di Brera. His earliest works are the frescoes in the Caglio parish church, which he completed in 1777.
Between 1790 and 1791, he undertook trips to Rome, Parma, Bologna, Florence and Naples. In 1793, he began painting the frescoes in S. Maria presso S. Celso. This was followed by a trip to Parma, and in November 1795, Appiani was inducted into the court.
Andrea Appiani was named "Commissario Superiore" and was responsible for selecting the art works in Lombardy and Veneto that were to be delivered to Venice. He was also commissioned to design letterheads for official documents, and anatomy models for medicine.
In 1801, the government commissioned Jacques-Louis David (1748–1825) and Appiani to paint "Napoleon brings peace to Europe". As commissar for visual arts, Andrea Appiani compiled an inventory of the archbishop’s picture collection, from which he selected 23 paintings to exchange for paintings from Brera. He also completed a report on the causes of the deterioration of Leonardo’s "Last Supper".
In 1803, Andrea Appiani travelled to Bologna and Parma in his capacity as commissar. A commission has verified that the boards for the frescoes in Palazzo Reale depicting the "Apotheosis of Napoleon as Triumphant Jupiter and the fall of the Colossi", are Andrea Appiani’s work.
Appiani travelled to Paris to participate in Napoleon’s coronation, where he met Jacques-Louis David in person. Appiani now belonged to a commission of artists and academics responsible for overseeing the consolidation of art works in the French capital. In May 1805, Appiani also took part in Napoleon’s coronation in Milan.
Napoleon I named Andrea Appiani his "first court painter" and commissioned him to paint works in the Palazzo Reale in Milan. In 1808, he began a series of frescoes depicting "Napoleon’s Apotheosis" and the four sovereign virtues in the Palazzo’s throne room. He also decorated the Palazzo’s Sala Rotonda with allegorical frescoes "Hymen and Pax", followed by "Falling Colossus". In 1813, a stroke rendered him almost unable to work. The paintings "The Story of Jupiter and Juno" for the Palazzo Regale’s Sala della Lanterna, and "Apotheosis of Psyche" for the minister Aldino Bologna remained unfinished.
Andrea Appiani died on 8th November 1817 in Milan.